Edison's major innovation was the first industrial research lab, which was built in
Menlo Park, New Jersey. It was the first institution set up with the specific purpose of producing constant technological innovation and improvement. Edison was legally attributed with most of the inventions produced there, though many employees carried out research and development work under his direction.
William Joseph Hammer, a consulting
electrical engineer, began his duties as a laboratory assistant to Edison in December 1879. He assisted in experiments on the
telephone, phonograph,
electric railway,
iron ore separator,
electric lighting, and other developing inventions. However, Hammer worked primarily on the incandescent electric lamp and was put in charge of tests and records on that device. In 1880, he was appointed chief engineer of the Edison Lamp Works. In his first year, the plant under General Manager
Francis Robbins Upton turned out 50,000 lamps. According to Edison, Hammer was "a pioneer of incandescent electric lighting."
Nearly all of Edison's patents were utility patents, which were protected for a 17 year period and included inventions or processes that are electrical, mechanical, or chemical in nature. About a dozen were design patents, which protect an ornamental design for up to a 14 year period. Like most patents, the inventions he described were improvements over
prior art. The phonograph patent, on the other hand, was unprecedented as the first device to record and reproduce sounds. Edison did not invent the first electric light bulb, but instead invented the first commercially practical incandescent light. Several designs had already been developed by earlier inventors including the patent he purchased from
Henry Woodward and
Mathew Evans,
Moses G. Farmer,
Joseph Swan,
James Bowman Lindsay, William Sawyer,
Sir Humphry Davy, and
Heinrich Göbel. Some of these early bulbs had such flaws as extremely short life, high expense to produce, and high current draw, making them difficult to apply on a large scale commercially. In 1878, Edison applied the term
filament to the
element of glowing wire carrying the current, although English inventor
Joseph Swan had used the term prior to this. Edison took the features of these earlier designs and set his workers to the task of creating longer-lasting bulbs. By 1879, he had produced a new concept: a high resistance lamp in a very high vacuum, which would burn for hundreds of hours. While the earlier inventors had produced electric lighting in laboratory conditions dating back to a demonstration of a glowing wire by
Alessandro Volta in 1800, Edison concentrated on commercial application and was able to sell the concept to homes and businesses by mass-producing relatively long-lasting light bulbs and creating a complete system for the generation and distribution of
electricity.
The Menlo Park research lab was made possible by the sale of the
quadruplex telegraph that Edison invented in 1874, which could send four simultaneous telegraph signals over the same wire. When Edison asked
Western Union to make an offer, he was shocked at the unexpectedly large amount that Western Union offered; the patent rights were sold for $10,000. The quadruplex telegraph was Edison's first big financial success.
In just over a decade Edison's Menlo Park laboratory had expanded to consume two city blocks. Edison said he wanted the lab to have "a stock of almost every conceivable material." A newspaper article printed in 1887 reveals the seriousness of his claim, stating the lab contained "eight thousand kinds of chemicals, every kind of screw made, every size of needle, every kind of cord or wire, hair of humans, horses, hogs, cows, rabbits, goats, minx, camels...silk in every texture, cocoons, various kinds of hoofs, shark's teeth, deer horns, tortoise shell...cork, resin, varnish and oil, ostrich feathers, a peacock's tail, jet, amber, rubber, all ores..." and the list goes on.
With Menlo Park, Edison had created the first industrial laboratory concerned with creating knowledge and then controlling its application.